Mineral wool composition

ABSTRACT

Mineral wool capable of dissolving in a physiological medium, which mineral wool comprises the constituents below in the following percentages by weight: 
     
       
         
               
               
               
               
               
             
                   
                   
               
                   
                 SiO 2   
                 39-55%, 
                 preferably 
                 40-52% 
               
                   
                 Al 2 O 3   
                 16-27%, 
                 ″ 
                 16-25% 
               
                   
                 CaO 
                  3-35%, 
                 ″ 
                 10-25% 
               
                   
                 MgO 
                  0-15%, 
                 ″ 
                  0-10% 
               
                   
                 Na 2 O 
                  0-15%, 
                 ″ 
                  6-12% 
               
                   
                 K 2 O 
                  0-15%, 
                 ″ 
                  3-12% 
               
                   
                 R 2 O (Na 2 O + K 2 O) 
                 10-17%, 
                 ″ 
                 12-17% 
               
                   
                 P 2 O 5   
                 0-3%, 
                 ″ 
                 0-2% 
               
                   
                 Fe 2 O 3   
                  0-15%, 
                   
               
                   
                 B 2 O 3   
                 0-8%, 
                 ″ 
                 0-4% 
               
                   
                 TiO 2   
                 0-3%, 
               
                   
                   
               
           
              
             
             
              
              
              
              
              
              
              
              
              
              
              
              
             
          
         
       
     
     and in that MgO is between 0 and 5%, especially between 0 and 2%, when R 2 O≦13.0%.

The present invention relates to the field of artificial mineral wools.It is aimed more particularly at mineral wools intended formanufacturing thermal and/or acoustic insulation materials orsoilless-culture substrates.

It concerns more particularly mineral wools of the rock-wool type, thatis to say the chemical compositions of which wools involve a highliquidus temperature and a high fluidity at their fiberizingtemperature, combined with a high glass transition temperature.

Conventionally, this type of mineral wool is fiberized by so-called“external” centrifuging processes, for example of the type of thoseusing a cascade of centrifuging wheels fed with molten material by astatic delivery device, as described in particular in PatentsEP-0,465,310 or EP-0,439,385.

The so-called “internal” centrifuging fiberizing process, that is to saythat using centrifuges rotating at high speed and drilled with holes,is, on the other hand, conventionally reserved for fiberizing mineralwool of the glass-wool type, schematically having a composition richerin alkali metal oxides and having a low alumina content, a lowerliquidus temperature and a higher viscosity at the fiberizingtemperature than rock wool. This process is described, in particular, inPatents EP-0,189,354 and EP-0,519,797.

However, technical solutions have recently been developed which make itpossible to adapt the internal centrifuging process to the fiberizing ofrock wool, especially by modifying the composition of the constituentmaterial of the centrifuges and their operating parameters. For furtherdetails on this subject, reference may be made especially to Patent WO93/02977. This adaptation has proved to be particularly beneficial inthe sense that it allows properties which hitherto were inherent in oneor other of the two types of wool—rock wool or glass wool—to becombined. Thus, the rock wool obtained by internal centrifuging has aquality comparable to that of glass wool, with a lower content ofunfiberized material than rock wool obtained conventionally. However, itretains the two major advantages associated with its chemical nature,namely a low chemicals cost and a high temperature withstand capability.

There are therefore now two possible ways of fiberizing rock wool, thechoice of one or other depending on a number of criteria, including thequality level required for the intended application and the level ofindustrial and economic feasibility.

To these criteria have in recent years been added that ofbiodegradability of mineral wool, namely its ability to be rapidlydissolved in a physiological medium, so as to prevent any potentialpathogenic risk associated with the possible accumulation of the finestfibres in the body by inhalation.

One solution to the problem of choosing the composition of a rock-typemineral wool having a biosoluble nature consists in the use of a highcontent of alumina and moderate alkali contents.

This solution results in particular in high raw materials costs becauseof the preferred use of bauxite.

The object of the present invention is to improve the chemicalcomposition of rock-type mineral wools, the improvement being aimedespecially at increasing their biodegradability with the ability forthem to be fiberized especially and advantageously by internalcentrifuging, while still maintaining the possibility of obtaining thesecompositions from inexpensive raw materials.

The subject of the invention is a mineral wool capable of dissolving ina physiological medium, which mineral wool comprises the constituentsbelow in the following percentages by weight:

SiO₂ 39-55%, preferably 40-52% Al₂O₃ 16-27%, ″ 16-25% CaO  3-35%, ″10-25% MgO  0-15%, ″  0-10% Na₂O  0-15%, ″  6-12% K₂O  0-15%, ″  3-12%R₂O (Na₂O + K₂O) 10-17%, ″ 12-17% P₂O₅ 0-3%, ″ 0-2% Fe₂O₃  0-15%, B₂O₃0-8%, ″ 0-4% TiO₂ 0-3%,

and in that MgO is between 0 and 5%, especially between 0 and 2%, whenR₂O≦13.0%.

According to an advantageous embodiment of the invention, the mineralwool comprises the constituents below in the following percentages byweight:

SiO₂ 39-55%, preferably 40-52% Al₂O₃ 16-25%, ″ 17-22% CaO 3-35%, ″10-25% MgO 0-15%, ″ 0-10% Na₂O 0-15%, ″ 6-12% K₂O 0-15%, ″ 6-12% R₂O(Na₂O + K₂O) 13.0-17%, P₂O₅ 0-3%, ″ 0-2% Fe₂O₃ 0-15%, B₂O₃ 0-8%, ″ 0-4%TiO₂ 0-3%,

In the rest of the text, any percentage of a constituent of thecomposition should be understood to mean a percentage by weight and thecompositions according to the invention may include up to 2 or 3% ofcompounds to be considered as unanalysed impurities, as is known in thiskind of composition.

The selection of such a composition has allowed a whole raft ofadvantages to be combined, especially by varying the many and complexroles that a number of these specific constituents play.

It has in fact been able to be shown that the combination of a highalumina content, of between 16 and 27%, preferably greater than 17%and/or preferably less than 25%, especially less than 22%, for a sum ofnetwork formers—silica and alumina—of between 57 and 75%, preferablygreater than 60% and/or preferably less than 72%, especially less than70%, with a high amount of alkalis (R₂O: soda and potash) of between 10and 17%, with an MgO content of between 0 and 5%, especially between 0and 2%, when R₂O≦13.0%, makes it possible to obtain glass compositionshaving the remarkable property of being fiberizable over a very widetemperature range and of endowing the fibres obtained with biosolubilityat acid pH. Depending on the embodiiments of the invention, the alkalicontent is preferably greater than 12%, especially greater than 13.0%and even 13.3%, and/or preferably less than 15%, especially less than14.5%.

This range of compositions proves to be particularly beneficial as ithas been able to be observed that, contrary to the received opinions,the viscosity of the molten glass does not drop significantly withincreasing alkali content. This remarkable effect makes it possible toincrease the difference between the temperature corresponding to theviscosity for fiberizing and the liquidus temperature of the phase whichcrystallizes, and thus to considerably improve the fiberizingconditions, and especially makes it possible to fiberize a new family ofbiosoluble glasses by internal centrifuging.

According to one embodiment of the invention, the compositions have ironoxide contents of between 0 and 5%, especially greater than 0.5% and/orless than 3%, especially less than 2.5%. Another embodiment is obtainedwith compositions which have iron oxide contents of between 5 and 12%,especially between 5 and 8%, which may allow mineral-wool blankets toexhibit fire resistance.

Advantageously, the compositions according to the invention satisfy therelationship:

(Na₂O+K₂O)/Al₂O₃≧0.5, preferably (Na₂O+K₂O)/Al₂O₃≧0.6, especially(Na₂O+K₂O)/Al₂O₃≧0.7,

which appears to favour the obtaining of a temperature corresponding tothe viscosity for fiberizing which is greater than the liquidustemperature.

According to a variant of the invention, the compositions according tothe invention preferably have a lime content of between 10 and 25%,especially greater than 12%, preferably greater than 15% and/orpreferably less than 23%, especially less than 20%, and even less than17%, combined with a magnesia content of between 0 and 5%, withpreferably less than 2% magnesia, especially less than 1% magnesiaand/or a magnesia content of greater than 0.3%, especially greater than0.5%.

According to another variant, the magnesia content is between 5 and 10%for a lime content of between 5 and 15%, and preferably between 5 and10%.

Adding P₂O₅, which is optional, at contents of between 0 and 3%,especially greater than 0.5% and/or less than 2%, may allow thebiosolubility at neutral pH to be increased. Optionally, the compositionmay also contain boron oxide which may allow the thermal properties ofthe mineral wool to be improved, especially by tending to lower itscoefficient of thermal conductivity in the radiative component and alsoto increase the biosolubility at neutral pH. Optionally, TiO₂ may alsobe included in the composition, for example up to 3%. Other oxides, suchas BaO, SrO, MnO, Cr₂O₃ and ZrO₂, may be present in the composition,each up to contents of approximately 2%.

The difference between the temperature corresponding to a viscosity of10^(2,6) poise (decipascal.second), denoted T_(log 2.5), and theliquidus of the crystallizing phase, denoted T_(liq), is preferably atleast 10° C. This difference, T_(log 2.5)−T_(liq), defines the “workingrange” of the compositions of the invention, that is to say the range oftemperatures within which it is possible to fiberize, most particularlyby internal centrifuging. This difference is preferably at least 20 or30° C., and even more than 50° C., especially more than 100° C.

The compositions according to the invention have high glass transitiontemperatures, especially greater than 600° C. Their annealingtemperature (denoted T_(annealing)) is especially greater than 600° C.

As mentioned above, the mineral wools have a satisfactory level ofbiosolubility, especially at acid pH. Thus, they generally have a rateof dissolution, especially measured with regard to silica, of at least30 and preferably of at least 40 or 50 ng/cm² per hour measured at pH4.5.

Another very important advantage of the invention concerns thepossibility of using inexpensive raw materials for obtaining thecomposition of these glasses. These compositions may especially resultfrom the melting of rocks, for example of the phonolite type, with analkaline-earth carrier, for example limestone or dolomite, if necessarysupplemented with iron ore. By this means, an alumina carrier ofmoderate cost is obtained.

This type of composition, having a high alumina content and a highalkali content, may be advantageously melted in fired or electric glassfurnaces.

Further details and advantageous characteristics will emerge from thedescription below of non-limiting preferred embodiments.

Table 1 below gives the chemical compositions, in percentages by weight,of five examples.

When the sum of all the contents of all the compounds is slightly lessor slightly greater than 100%, it should be understood that thedifference from 100% corresponds to the unanalysed minorityimpurities/components and/or is due merely to the accepted approximationin this field in the analytical methods used.

TABLE 1 EX.1 EX. 2 EX. 3 EX. 4 Ex. 5 SiO₂ 47.7 42.6 44.4 45.2 45.4 A₂O₃18.6 18.1 17.3 17.2 18.1 CaO 6.2 22.7 21.7 15.3 13.5 MgO 7.1 0.2 0.4 0.50.5 Na₂O 8.0 6.3 6.O 6.2 6.5 K₂O 5.2 7.4 7.1 7.8 8.1 Fe₂O₃ 7.2 2.5 3 6.67.3 TOTAL 100 99.8 99.9 98.8 99.4 SiO₂ ₊ 66.3 60.7 61.7 62.4 63.5 Al₂O₃Na₂O + K₂O 13.2 13.7 13.1 14 14.6 (Na₂O + 0.71 0.76 0.76 0.81 0.81K₂O)/Al₂O₃ T_(log 2.5) 1293° C. 1239° C. 1230° C. 1248° C. 1280° C.T_(11g) 1260° C. 1200° C. 1190° C. 1160° C. 1160° C. T_(log 2.5) −T_(11g) +33° C. +39° C. +40° C. +88° C. +120° C. T_(annealing) 622° C.658° C. 634° C. 631° C. Dissolution ≧30 ≧30 ≧30 107 107 rate at pH =ng/cm² ng/cm² ng/cm² ng/cm² ng/cm² 4.5 per h per h per h per h per h

The compositions according to these examples were fiberized by internalcentrifuging, especially according to the teaching of the aforementionedPatent WO 93/02977.

The working ranges, defined by the difference T_(log 2,5)−T_(liq), arelargely positive. All have a (Na₂O+K₂O)/Al₂O₃ ratio of greater than 0.7for a high alumina content of approximately 17 to 20%, with quite a high(SiO₂+Al₂O₃) sum and an alkali content of at least 13.0%.

Examples of additional compositions according to the invention (referredto as Ex. 6 to Ex. 40) have proved to be beneficial and are given inTable 2.

All have a (Na₂O+K₂O)/Al₂O₃ ratio of greater than 0.5, especiallygreater than 0.6, even greater than 0.7.

The alumina content is high, between 17% and more than 25%, with a quitehigh (SiO₂+Al₂O₃) sum, especially greater than 60%.

The alcali content of the additional compositions is especially betweenless than 11.5% and more than 14%.

It should be noted that their working ranges are largely positive,especially greater than 50° C., indeed greater than 100° C. and evengreater than 150° C.

The liquidus temperatures are not very high, especially less than orequal to 1200° C. and even 1150° C.

The temperatures (T_(log 2.5)) corresponding to viscosities of 10^(2.5)poise are compatible with the use of high-temperature fiberizing dishes,especially under the conditions of use that are described in ApplicationWO93/02977.

The preferred compositions are especially those in which T_(log 2.5) isless than 1350° C., preferably less than 1300° C.

It has been able to be shown that for compositions comprising between 0and 5% magnesia MgO, especially with at least 0.5% of MgO and/or lessthan 2%, or even less than 1%, of MgO and between 10 and 13% of alkalis,very satisfactory values of physical properties, especially workingranges and rate of dissolution, are obtained (in the Case of examples:Ex. 18, Ex. 31, Ex. 32, Ex. 33 and ex. 35 to Ex. 40).

It should be noted that their Annealing temperatures are especiallygreater than 600° C., even greater than 620° C., and even greater than630° C.

TABLE 2 EX. 6 EX. 7 EX. 8 EX. 9 EX. 10 EX. 11 EX. 12 EX. 13 EX. 14 EX.15 SiO₂ 43.9 44.2 43.8 46.1 43.8 47.1 41.9 48.2 43.2 46.3 Al₂O₃ 17.617.6 17.6 17.4 17.6 15.7 20.9 19.8 22.5 19.3 CaO 15 13.3 14.2 13.2 11.99.8 14.5 14 14.3 13.9 MgO 0.5 0.5 0.5 0.5 0.5 0.4 0.5 0.5 0.5 0.5 Na₂O6.40 6.3 6.4 6.3 6.4 6.4 6.1 6 6 6 K₂O 7.6 7.9 7.9 7.8 8.0 8.0 7.4 7.27.1 7.1 Fe₂O₃ 8.4 9.8 9.2 8.3 11.3 12.1 8.7 4.2 6.3 6.8 TOTAL 99.4 99.699.6 99.6 99.5 99.5 100 99.9 99.9 99.9 SiO₂ + Al₂O₃ 61.5 61.8 61.4 63.561.4 62.8 62.8 68 65.7 65.6 Na₂O + K₂O 14.2 14.2 14.3 14.1 14.4 14.413.5 13.2 13.1 13.1 (Na₂O + K₂O)/Al₂O₃ 0.81 0.81 0.81 0.81 0.81 0.920.65 0.67 0.58 0.66 T_(log 2.5+) (in ° C.) 1270 1285 1275 1310 1295 13051300 1380 1345 1335 T_(lig) (in ° C.) 1120 1100 1110 1140 1160 1200 11401160 1140 1110 T_(log 2.5) − T_(liq) 150 185 165 170 135 105 160 220 205225 (in ° C.) T_(annealing) (in ° C.) 618 615 616 635 654 655 645Dissolution rate 45 ≧30 ≧30 ≧30 60 >30 ≧30 ≧30 ≧30 ≧30 at pH = 4.5 (inng/cm² per hour) EX. 16 EX. 17 EX. 18 EX. 19 EX. 20 EX. 21 EX. 22 EX. 23EX. 24 EX. 25 SiO₂ 45.4 43 44.3 43 47.7 45.6 43.5 43.1 40.3 42.3 Al₂O₃18.8 19.7 19.8 21.5 18.4 22.4 21.2 22.2 25.1 21.7 CaO 13.9 14.1 13.414.1 13.8 13.9 14.1 14 13.9 13.1 MgO 0.5 0.5 0.7 0.5 0.5 0.5 0.5 0.5 0.50.6 Na₂O 5.9 6 8.3 6 6 6 6 6 6 5.9 K₂O 7.2 7.2 3.7 7.3 7.3 7.3 7.2 7.27.2 7.7 Fe₂O₃ 8.3 9.5 9.3 7.5 6.2 4.2 7.4 6.9 6.9 8.7 TOTAL 100 100 99.599.8 99.9 99.9 99.9 99.9 99.9 100 SiO₂ + Al₂O₃ 64.2 62.7 63.8 64.5 66.168 64.7 65.3 65.4 64.0 Na₂O + K₂O 13.1 13.2 12 13.3 13.3 13.3 13.2 13.213.2 13.6 (Na₂O + K₂O)/Al₂O₃ 0.7 0.67 0.61 0.62 0.72 0.59 0.62 0.59 0.530.63 T_(log 2.5+) (in ° C.) 1315 1305 1250 1325 1345 1370 1325 1335 13301300 T_(lig) (in ° C.) 1110 1110 1170 1140 1150 1150 1120 1160 1170 1160T_(log 2.5) − T_(liq) 205 195 80 175 195 220 205 175 160 140 (in ° C.)T_(annealing) (in ° C.) 637 638 644 645 658 644 650 652 Dissolution rate≧30 ≧30 ≧30 ≧30 ≧30 >30 ≧30 ≧30 ≧30 ≧30 at pH = 4.5 (in ng/cm² per hour)EX. 26 EX. 27 EX. 28 EX. 29 EX. 30 EX. 31 EX. 32 EX. 33 EX. 34 SiO₂ 43.941.5 39.3 47.3 45.3 45.3 44 46.5 46.5 Al₂O₃ 24.6 24.7 24.9 18.2 19.220.5 22.5 19.2 19.5 CaO 13.2 13.4 13.3 13.9 12.9 12.9 12.7 12.4 11.5 MgO0.6 0.6 0.5 0.6 0.8 0.8 0.8 0.8 0.7 Na₂O 5.9 6.2 6.3 8.1 7.9 8.3 7.9 8.88.4 K₂O 7.6 7.6 7.6 3.9 5.7 3.8 3.7 3.9 5 Fe₂O₃ 4 6 8.1 7.5 7.5 7.4 7.57.4 7.5 TOTAL 99.8 100 100 99.5 99.3 99 99.1 99 99.1 SiO₂ + Al₂O₃ 68.566.2 64.2 65.5 64.5 65.8 66.5 65.7 66 Na₂O + K₂O 13.5 12.8 13.9 11.913.6 12.1 11.6 12.7 13.4 (Na₂O + K₂O)/Al₂O₃ 0.55 0.52 0.56 0.65 0.7 0.590.52 0.66 0.69 T_(log 2.5+) (in ° C.) 1370 1330 1295 1270 1270 1280 12851280 1295 T_(lig) (in ° C.) 1180 1200 1160 1150 1180 1200 1150 1170T_(log 2.5) − T_(liq) 150 95 110 120 100 85 130 125 (in ° C.)T_(annealing) (in ° C.) 625 618 619 Dissolution rate ≧30 ≧30 ≧30 ≧30≧30 >30 ≧30 ≧30 ≧30 at pH = 4.5 (in ng/cm² per hour) EX. 35 EX. 36 EX.37 EX. 38 EX. 39 EX. 40 SiO₂ 47.7 46.5 48.0 47.1 46 46 Al₂O₃ 18.9 19.519.2 21 20.5 20.1 CaO 13.6 14.4 13.6 12.6 11.6 14.4 MgO 1.4 1.4 0.7 0.70.7 1.1 Na₂O 7.4 7.3 7.4 7.2 7.4 7.1 K₂O 5 5 5 5 5 5 Fe₂O₃ 4.8 4.9 4.94.9 7.3 4.9 TOTAL 99.8 99 98.8 98.5 98.5 98.6 SiO₂ + Al₂O₃ 66.6 66.067.2 68.1 66.5 66.1 Na₂O + K₂O 0.66 12.3 12.4 12.2 12.4 12.1 (Na₂O +K₂O)/Al₂O₃ 0.66 0.63 0.65 0.53 0.6 0.6 T_(log 2.5+) (in ° C.) 1310 12951315 1340 1320 1300 T_(lig) (in ° C.) 1140 1150 1120 1110 1120 1140T_(log 2.5) − T_(liq) (in ° C.) 170 145 195 230 200 160 T_(annealing)(in ° C.) 636 636 640 643 633 641 Dissolution rate at pH = 4.5 ≧30 ≧30≧30 ≧30 ≧30 ≧30 (in ng/cm² per hour)

What is claimed is:
 1. A mineral wool capable of dissolving in aphysiological medium, comprising the constituents: 39 to 55% by weightSiO₂, 16 to 27% by weight Al₂O₃, 3 to 35% by weight CaO, 0 to 15% byweight MgO, 0 to 15% by weight Na₂O, 0 to 15% by weight K₂O, 10 to 17%by weight R₂O(Na₂O+K₂O), 0 to 3% by weight P₂O₅, 0 to 15% by weightFe₂O₃, 0 to 8% by weight B₂O₃, and 0 to 3% by weight TiO₂, wherein MgOis between 0 and 5% when R₂O≦13.0%.
 2. The mineral wool of claim 1,wherein the constituents are in amount of 40 to 52% by weight SiO₂, 16to 25% by weight Al₂O₃, 10 to 25% by weight CaO, 0 to 10% by weight MgO,6 to 12% by weight Na₂O, 3 to 12% by weight K₂O, 12 to 17% by weightR₂O(Na₂O+K₂O), 0 to 2% by weight P₂O₅, 0 to 15% by weight Fe₂O₃, 0 to 4%by weight B₂O₃, and 0 to 3% by weight of TiO₂.
 3. The mineral wool ofclaim 1, wherein MgO is in amount of 0 to 5% by weight.
 4. The mineralwool of claim 1, wherein R₂O≦13.0% by weight and MgO is in an amount of0 to 2%.
 5. The mineral wool of claim 1, wherein the constituents are inamount of 40 to 52% by weight SiO₂, 16 to 25% by weight Al₂O₃, 3 to 35%by weight CaO, 0 to 15% by weight MgO, 0 to 15% by weight Na₂O, 0 to 15%by weight K₂O, 13.0 to 17% by weight R₂O(Na₂O+K₂O), 0 to 3% by weightP₂O₅, 0 to 15% by weight Fe₂O₃, 0 to 8% by weight B₂O₃, and 0 to 3% byweight of TiO₂.
 6. The mineral wool of claim 5, wherein the constituentsare in amount of 40 to 52% by weight SiO₂, 17 to 22% by weight Al₂O₃, 10to 25% by weight CaO, 0 to 10% by weight MgO, 6 to 12% by weight Na₂O, 6to 12% by weight K₂O, 13.0 to 17% by weight R₂O(Na₂O+K₂O), 0 to 2% byweight P₂O₅, 0 to 15% by weight Fe₂O₃, 0 to 4% by weight B₂O₃, and 0 to3% by weight of TiO₂.
 7. The mineral wool of claim 1, wherein R₂O is inan amount from 13.0 to 15.0% by weight.
 8. The mineral wool of claim 7,wherein R₂O is in an amount from 13.3 to 14.5% by weight.
 9. The mineralwool of claim 1, wherein Fe₂O₃ is in an amount from 0 to 5% by weight.10. The mineral wool of claim 9, wherein Fe₂O₃ is in an amount from 0 to3% by weight.
 11. The mineral wool of claim 9, wherein Fe₂O₃ is in anamount from 0 to 2.5% by weight.
 12. The mineral wool of claim 11,wherein Fe₂O₃ is in an amount from 5 to 15% by weight.
 13. The mineralwool of claim 12, wherein Fe₂O₃ is in an amount from 5 to 8% by weight.14. The mineral wool of claim 1, wherein the weight ratio(Na₂O+K₂O)/Al₂O₃≧0.5.
 15. The mineral wool of claim 1, wherein theweight ratio (Na₂O+K₂O)/Al₂O₃≧0.6.
 16. The mineral wool of claim 15,wherein the weight ratio (Na₂O+K₂O)/Al₂O₃≧0.7.
 17. The mineral wool ofclaim 1, wherein CaO is in amount from 10 to 25% by weight and MgO is inan amount from 0 to 5% by weight.
 18. The mineral wool of claim 17,wherein CaO is in amount from 15 to 25% by weight and MgO is in anamount from 0 to 2% by weight.
 19. The mineral wool of claim 18, whereinMgO is in an amount from 0 to 1% by weight.
 20. The mineral wool ofclaim 1, wherein the MgO is in an amount from 5 to 10% by weight and CaOis in an amount from 5 to 15% by weight.
 21. The mineral wool of claim20, wherein CaO is in an amount from 5 to 10% by weight.
 22. The mineralwool of claim 1, wherein the mineral wool has a rate of dissolution ofat least 30 ng/cm² per hour measured at pH 4.5.
 23. A method of making amineral wool, the method comprising fiberizing a glass produced bymelting raw materials and an alkaline-earth carrier; and forming themineral wool of claim
 1. 24. The method of claim 23, wherein said rawmaterials are rocks.
 25. The method of claim 24, wherein said rocks arephonolite.
 26. The method of claim 23, wherein said alkaline-earthcarrier is limestone or dolomite.
 27. The method of claim 25, furthercomprising melting iron ore with the raw materials and thealkaline-earth carrier.
 28. The method of claim 22, wherein saidfiberizing a glass comprises internal centrifuging.